Noise reduction method for applying high polymer coating on surface of propeller

Abstract

The invention belongs to the field of propellers, and discloses a noise reduction method for applying an epoxy resin coating on the surface of a propeller, which comprises the following steps of: adhering polyurea, polyurethane or epoxy resin to the surface of the propeller in manners of spraying, dip-coating, brush coating, spot coating and the like to form a compact protective film and hemispherical turbulent flow bulges, changing eddy current on the surface of the propeller, and realizing noise reduction. The protrusions are arranged to two thirds of the radius along the front edge of the propeller pressure face, and the size of the protrusions can be optimized according to working conditions. The method is simple and easy to implement, the noise sound pressure level is effectively reduced, environmental noise pollution is reduced, and the aircraft sound stealth performance is improved. Experiments show that under the rotating speed of 2000 rpm, the noise reduction effect is remarkable, and the thrust loss is only 0.37%. According to the noise reduction method, the aerodynamic noise of the propeller can be effectively reduced on the premise of ensuring the aerodynamic performance of the propeller, the sound concealment performance of an aircraft is improved, the noise pollution to the surrounding environment is reduced, and the method is simple, easy to implement and easy to popularize.

Description

Technical Field

[0001] The invention belongs to the field of propellers and relates to a noise reduction method for applying a polymer coating on the surface of a propeller. Background Art

[0002] A propeller is a device that converts the engine's rotational power into propulsion by rotating blades in the air or water. It may have two or more blades connected to the hub, and the rearward side of the blades is a spiral surface or a propeller that is close to a spiral surface.

[0003] During the use of aircraft propellers provided in the prior art, there is a problem of too much propeller noise. In the military field, excessive noise is not conducive to the concealment of the aircraft; in the civilian field, drones often fail to meet the noise standards for low-altitude flights over cities and are restricted from use due to the problem of disturbing the public. The propulsion efficiency and noise issues of propellers are key factors in propeller design. However, existing noise reduction methods cannot solve the propeller noise problem well. For example, adding a serrated structure to the leading and trailing edges of the propeller is easy to damage due to stress concentration problems, and the maintenance cost is high. Therefore, how to provide a simple, easy-to-use and easy-to-promote propeller noise reduction method has become a technical problem that needs to be solved urgently by those skilled in the art.

[0004] With the development of technology, new polymer coatings are constantly being developed. A class of polymer materials with high temperature resistance, corrosion resistance and high strength, such as polyurea, epoxy resin, polyurethane, etc., are widely used in the preparation of drag and noise reduction coatings because of their impact resistance, good adhesion, low modulus, low damping and dense and impermeable coatings. They are widely used in the aerospace field and provide new possibilities for propeller noise reduction. Summary of the invention

[0005] The purpose of the present invention is to provide a noise reduction method for applying a polymer coating on the surface of a propeller, which can effectively reduce the aerodynamic noise of the propeller while ensuring the aerodynamic performance of the propeller, and is simple, easy to implement and easy to promote.

[0006] The technical solution of the present invention:

[0007] A noise reduction method for applying a polymer coating on the surface of a propeller, wherein the polymer material is attached to the surface of the propeller by spraying, dipping or brushing to form a dense polymer film and form turbulent protrusions on the surface of the propeller. Without changing the aerodynamic performance of the airfoil too much, the geometric condition of the propeller surface is changed, thereby changing the vortex on the propeller surface and its flow rate, so as to achieve the purpose of noise reduction.

[0008] Furthermore, the spoiler protrusions are regular protrusions formed after the polymer material solidifies. The protrusions are hemispherical and are arranged in an array along the leading edge on the propeller pressure surface. The distance from the trailing edge to the propeller rotation center is 2 / 3 of the entire propeller radius.

[0009] Furthermore, the radius of the hemispherical protrusion and the distance between the sphere centers can be adjusted, and can be optimized according to the propeller size and the corresponding working conditions, and the optimal radius value can be found based on the noise and thrust values ​​obtained from the test.

[0010] Furthermore, the method of applying the polymer material to the propeller surface includes but is not limited to directly spraying, dipping, brushing, spot coating on the propeller surface, and placing the polymer material on the propeller surface after pouring it into a mold.

[0011] Furthermore, the specific composition content of polymer coatings can be selected differently according to the working environment of the propeller, such as polyurea coatings, polyurethane coatings, epoxy resin coatings, etc. Since propellers are key equipment for maintaining aircraft power and are often located in front of or behind aircraft engines, and have high-temperature airflow fields in the working environment, the selected polymer coatings are usually required to have the characteristics of high temperature resistance, waterproof and oil resistance, high strength, and stable chemical properties.

[0012] Beneficial effects of the present invention: The method for reducing propeller aerodynamic noise provided by the present invention forms a protective film and turbulent geometric protrusions on the propeller surface by spraying, dipping or brushing a polymer coating on the propeller surface, thereby reducing the eddy convection velocity without changing the aerodynamic performance of the airfoil, thereby reducing the aerodynamic noise generated by the rotation of the propeller blades without changing the aerodynamic performance too much, and then effectively reducing the sound pressure level of the propeller noise while ensuring the aerodynamic performance of the propeller, reducing noise pollution to the surrounding environment, and improving the acoustic stealth performance of the aircraft. The noise reduction method is simple and easy to implement and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram of the propeller appearance described in the embodiment;

[0014] Figure 2 This is a diagram showing the appearance of the propeller after a polymer coating is sprayed on the surface of the propeller in the embodiment to form spoiler bulges;

[0015] Figure 3 This is a partial view of the blade, in which the hemispherical shape is a spoiler protrusion formed by the polymer coating;

[0016] Figure 4 A noise reduction test of propeller aerodynamic noise provided in an embodiment of the present application is provided, and a curve chart showing the comparison results of the total noise intensity of an original propeller and a propeller sprayed with a polymer coating when the rotation speed is 2000 rpm and the incoming flow velocity is 6 m / s. DETAILED DESCRIPTION

[0017] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0018] A noise reduction method for applying a polymer coating on the propeller surface can effectively reduce the propeller aerodynamic noise level while ensuring the propeller aerodynamic performance, and is simple, easy to implement and easy to promote.

[0019] Please refer to Figure 1 , Figure 1 This is an appearance diagram of a drone propeller provided in an embodiment of the present application.

[0020] In this embodiment, the propeller is a three-blade propeller with a diameter of 0.8 m and is made of yellow-green photosensitive resin.

[0021] In this embodiment, the step of spraying the polymer coating on the propeller includes:

[0022] Pre-treating the propeller to remove dirt on the surface of the propeller;

[0023] Spraying polyurea coating uniformly and at a constant speed on the surface of the pretreated propeller;

[0024] Curing the polymer coating sprayed on the surface of the propeller;

[0025] Place the mold on the propeller surface and spray the polyurea coating again;

[0026] The mold is removed to determine whether the thickness, appearance and contact angle of the polymer coating sprayed on the surface of the propeller meet the requirements;

[0027] If any one of the thickness, appearance and contact angle of the polymer coating sprayed on the surface of the propeller does not meet the requirements, the polymer coating is re-sprayed.

[0028] Optionally, judging whether the contact angle of the polymer coating sprayed on the surface of the propeller meets the requirement includes:

[0029] Using a contact angle measuring instrument to check the static contact angle of the propeller surface after the polymer coating is sprayed, and determine whether the static contact angle is less than 10°;

[0030] If the static contact angle is less than 10°, the contact angle of the polymer coating sprayed on the surface of the propeller meets the requirement;

[0031] If the static contact angle is not less than 10°, the contact angle of the polymer coating sprayed on the surface of the propeller does not meet the requirement.

[0032] The steps of applying polymer coating to the propeller surface can be differently set according to actual application needs, using methods such as spraying, dipping, brushing, and spot coating. The protrusions can be formed by directly making relevant shapes on the propeller or by making and placing molds, that is, the formation can ensure the effect of coating application.

[0033] Specifically, after the polymer coating is sprayed on the propeller surface, the polymer coating sprayed on the propeller surface can be cured by a blower to accelerate the solidification of the polymer coating on the propeller surface. Further, it is determined whether the thickness, appearance and contact angle of the polymer coating sprayed on the propeller surface meet the requirements, that is, whether the thickness of the polymer coating sprayed on the propeller surface reaches the target thickness, whether there are macroscopic irregular protrusions and depressions visible to the naked eye after the polymer coating is sprayed on the propeller surface, and whether the microscopic static contact angle after the polymer coating is sprayed on the propeller meets the standard. Of course, this application does not limit the specific value of the above target thickness. It can be set appropriately or simulated and optimized according to the actual application needs. For example, the target thickness in this embodiment is 1mm.

[0034] Specifically, in this embodiment, the optimal effect radius of the hemispherical protrusions after simulation optimization is 1 mm, the spacing is about 10 mm, and the number is 29.

[0035] Further, in order to test the implementation effect of the technical solution, the present embodiment sprays a polymer coating on the surface of the propeller, and when the polymer coating on the surface of the propeller and the geometric protrusions formed thereon are completely cured, Figure 2 and Figure 3 As shown in the figure, the propeller noise test was carried out on it. The sound pressure level of the original propeller and the propeller coated with polymer coating was measured by using a sound pressure sensor at a distance of 0.64m from the propeller rotation center. After the propeller kept rotating stably at 2000rpm for 10s, 15s test data was output. The measurement was performed three times and the average value was taken. The results show that under the same working conditions, that is, the speed is 2000rpm and the incoming flow velocity is 6m / s, the aerodynamic noise of the propeller sprayed with polymer coating is significantly reduced, as shown in the figure below. Figure 4 shown.

[0036] The test results show that the average thrust of the original propeller in three tests is 338.245N, and the average thrust of the propeller sprayed with polymer coating is 336.971N, with a difference of 1.274N and a thrust reduction of only 0.37%.

[0037] Compared with the propeller without the polymer coating, the peak value of the noise sound pressure level of the propeller with the polymer coating is reduced by 3dB under the working conditions corresponding to the present embodiment. Therefore, it is well verified that the propeller noise reduction method provided in the present application can effectively reduce the propeller aerodynamic noise.

[0038] The above is a detailed introduction to the propeller aerodynamic noise reduction method and device provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A noise reduction method using a polymer coating on the surface of a propeller, characterized in that: The polymer material is attached to the propeller surface by spraying, dipping, brushing or spot coating to form a dense polymer film and form spoiler protrusions in some areas of the propeller surface.

2. The noise reduction method according to claim 1, characterized in that: The spoiler protrusions are regular protrusions formed after the polymer material solidifies. The protrusions are hemispherical and arranged in an array along the leading edge of the propeller pressure surface. The distance from the trailing edge to the propeller rotation center is 2 / 3 of the entire propeller radius.

3. The noise reduction method according to claim 2, characterized in that: The radius of the hemispherical protrusions and the distance between the sphere centers are adjusted according to the propeller size and the corresponding working conditions.

4. The noise reduction method according to claim 1, characterized in that: The polymer material is polyurea coating, polyurethane coating or epoxy resin coating.

Images